We investigated the preparation of Pt and Pt/Ru bimetallic fine particles dispersed in polyimide particles by precipitation from various polyamic acid solutions containing Pt and Ru complexes, followed by the carbonization of the resulting polyimide particles. As Pt complexes, platinum(II) acetylacetonate [Pt(acac)(2)], trimethylplatinum iodide [PtIMe3], and (trimethyl) methylcyclopentadienylplatinum [Pt(MeCp) Me-3] were used. As Ru complexes, ruthenium(III) acetylacetonate [Ru(acac)(3)], acenaphthylene heptacarbonyl triruthenium [(C12H8) Ru-3(CO)(7)], and tetracarbonylbis(eta-cyclopentadienyl) diruthenium [Ru-2(CO)(4)Cp-2] were used. Bow tie-like polyimide particles containing Pt or Pt/Ru bimetallic particles could be obtained from pyromellitic dianhydride /m-phenylenediamine (PMDA/MPD) polyamic acid containing Pt and Ru complexes. Sheaf-like polyimide particles were obtained by using 4,4'-oxydianiline(ODA) as diamine. The morphologies of polyimide particles strongly depend on the kind and the concentration of Pt and Ru complexes. We could obtain Pt or Pt/Ru bimetallic fine particles dispersed in porous carbon particles, which morphologies are the same as the polyimide particles used as carbon precursors, by heat-treatment of the obtained polyimide particles. Pt and Pt/Ru fine particles in the range of 3similar to10 nm were contained in bow tie-like or sheaf-like carbon particles. The addition of Ru complexes to polyamic acid solutions decreased the sizes of Pt particles in carbon particles. (C) 2003 Kluwer Academic Publishers.